iOS 4.0 Wifi Help!

Okay, so I have a 32gig 2nd generation iPod touh and it was working perfectly fine until I upgraded to iOS4. After doing this the wifi says it's on but it doesn't show any networks. When anyone else with an iPod touch searches for networks up to 8 will show up but mine still shows none. I have seemed to try everything, re-installing iOS4, resetting network settings and even downgrading back to firmware 3.1.2 and 3.1.3. I require wifi for almost everything I do so this is a big problem. If anyone has any ideas they would be greatly appreciated!